JP2004293526A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump embodied in a lightweight construction capable of reducing the manufacturing cost. <P>SOLUTION: A suction side cover 36 of this fuel pump 10 is formed from resin, which makes light the construction and reduces the manufacturing cost. The cover 36 is furnished with a flange 34, which is caulked fast to a housing 22, when the stress due to caulking is concentrated on the flange 34 in the peripheral part of the cover 36, so that it is possible to suppress the risk that the central part of the cover 36 deforms convex in the direction of approaching an impeller 37, and the cover 36 can be prevented from contacting with the impeller 37. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel pump that supplies fuel in a fuel tank to an internal combustion engine (hereinafter, “internal combustion engine” is referred to as an engine).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a fuel pump that boosts fuel with an impeller accommodated in a boosting channel is known (see, for example, Patent Document 1). By replacing the metal parts with resin parts, the manufacturing cost of the fuel pump can be reduced and the weight can be reduced.
[0003]
[Patent Document 1]
Japanese Patent No. 3052623 [0004]
[Problems to be solved by the invention]
However, there is the following problem in replacing the suction side cover that is provided on the counter-motor side of the impeller and forms the pressure increasing flow path with a resin component. That is, as shown in FIG. 10, when the resin suction side cover 94 is caulked and joined to the cylindrical metal housing 92, the central portion of the suction side cover 94 is convexly deformed in a direction approaching the impeller 96, and the suction is performed. The side cover 94 and the impeller 96 may come into contact with each other, and the impeller 96 may be unable to rotate. Further, if the suction side cover 94 creeps due to a continuous load applied from the metal housing 92 to the suction side cover 94, the positioning effect of the suction side cover 94 due to caulking joining is lost, and the assembly position of the suction side cover 94 may be shifted. There is.
The present invention has been created in view of these problems, and an object thereof is to provide a fuel pump that is reduced in manufacturing cost and weight.
[0005]
[Means for Solving the Problems]
In the fuel pump according to the first aspect of the present invention, the manufacturing cost is reduced and the weight is reduced by forming the suction side cover with resin. By forming a flange on the suction side cover and caulking the flange to the housing, the stress due to caulking is concentrated on the flange on the outer periphery of the suction side cover, so the center of the suction side cover protrudes to the impeller side. It is possible to suppress distortion and prevent contact between the suction side cover and the impeller.
[0006]
In the fuel pump according to the second aspect of the present invention, the contact area of the flange with the housing is increased by rounding the outer peripheral corner portion of the flange that is caulked and joined to the housing on the side opposite to the pump casing. As a result, creep of the flange is suppressed, and the suction side cover positioning effect by caulking is maintained.
[0007]
As in the fuel pump according to claim 3 of the present invention, it is desirable that the radius of curvature of the outer peripheral corner portion of the flange on the side opposite to the pump casing is 2 mm or more.
As in the fuel pump according to claim 4 of the present invention, it is desirable that the flange and the housing are caulked and joined using a curved surface of a punch whose inclination angle with respect to the central axis of the housing increases toward the deeper side.
As in the fuel pump according to claim 5 of the present invention, the thickness of the flange is preferably 4 mm or more and 5 mm or less.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a fuel pump according to the present invention. The fuel pump 10 is, for example, an in-tank pump that is mounted in a fuel tank of a vehicle or the like.
[0009]
First, the overall configuration of the fuel pump 10 will be described.
The housing 22 is a cylindrical metal member. The thickness in the vicinity of both ends of the housing 22 is smaller than the thickness in the center, and annular step surfaces 20 and 30 are formed on the inner walls in the vicinity of both ends of the housing 22. The housing 22 accommodates the discharge side cover 14, the electric motor 46, the pump casing 40, the impeller 37, the suction side cover 36, and the like.
[0010]
The discharge-side cover 14 is inserted from one end of the housing 22 and is in contact with the step surface 20 of the housing 22. One end portion of the housing 22 is caulked and joined to the discharge side cover 14, whereby the discharge side cover 14 is sandwiched and positioned by the step surface 20 of the housing 22 and the end portion of the housing 22. A first bearing member 16 that supports the rotating shaft 45 of the electric motor 46 is fixed to the discharge side cover 14.
[0011]
Four arc-shaped permanent magnets 44 constituting the electric motor 46 are provided on the inner peripheral wall of the housing 22 at predetermined intervals. These permanent magnets 44 are arranged so that magnetic poles having different poles are alternately formed in the circumferential direction.
[0012]
The armature 42 constituting the electric motor 46 is accommodated in the housing 22 so as to be rotatable together with the rotating shaft 45. A commutator 18 is provided at one end of the armature 42. The rotating shaft 45 is press-fitted into the iron core 24. Coils 28 are wound around a plurality of bobbins 26 provided on the iron core 24. The commutator 18 is composed of a plurality of segments insulated from each other, and the coil 28 wound around each bobbin 26 is electrically connected to one of the segments of the commutator 18.
[0013]
The pump casing 40 is inserted from the other end of the housing 22 and is in contact with the stepped surface 30 of the housing 22. The peripheral edge portion of the pump armature 40 on the side opposite to the armature side and the peripheral edge portion of the suction side cover 36 are in annular contact. When the suction side cover 36 is caulked and joined to the housing 22, the pump casing 40 and the suction side cover 36 are sandwiched and positioned by the step surface 30 of the housing 22 and the end portion of the housing 22. A pressure increasing flow path 32 is formed between the suction side cover 36 and the pump casing 40. An impeller 37 is rotatably accommodated in the boost channel 32. A second bearing member 38 that supports the rotating shaft 45 of the electric motor 46 is fixed to the pump casing 40.
[0014]
A large number of blade grooves are formed on the outer periphery of the disk-shaped impeller 37. When the impeller 37 rotates together with the rotating shaft 45 of the electric motor 46, the fuel in the boost channel 32 is pressurized. The fuel in the fuel tank sucked into the boosting passage 32 from the fuel suction port 52 (see FIG. 2) formed in the suction side cover 36 is discharged from the boosting passage 32 through the communication passage 29 of the pump casing 40. Further, the fuel is discharged from the fuel pump 10 through the fuel discharge port 12 formed in the discharge side cover 14 and supplied to an engine (not shown).
[0015]
The overall configuration of the fuel pump 10 has been described above. Next, the caulking joint between the suction side cover 36 and the housing 22 will be described in detail. 2A is a plan view showing the suction side cover 36, FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 2C is a bottom view showing the suction side cover 36. .
[0016]
The suction side cover 36 is a substantially disk-shaped resin member, and a plurality of recesses 54 are formed to reduce dimensional errors due to material sink marks during molding. The main portion wall thickness t1 of the suction side cover 36 is desirably thin as long as durability can be secured in order to shorten the axial length of the fuel pump 10, and is set to 7 mm in this embodiment.
[0017]
The suction side cover 36 is formed with a C-shaped groove 50 for forming a pressure increasing flow path. At one end of the groove 50, a fuel inlet 52 for sucking fuel from the fuel tank is formed. A vapor hole 48 for discharging vapor generated in the pressure increasing flow path to the fuel tank is formed in the middle of the groove 50.
[0018]
Since the suction side cover 36 is formed with a flange 34, an annular step is formed on the outer wall of the suction side cover 36. The outer peripheral corner of the flange 34 on the side opposite to the pump housing is preferably rounded with a radius of curvature of 2 mm or more. As the radius of curvature of the outer peripheral corner of the flange 34 on the side opposite to the pump housing increases, the contact area between the flange 34 and the housing 22 increases, and stress concentration in the flange 34 due to caulking is reduced. When the stress concentration in the flange 34 is alleviated, creep of the flange 34 is prevented, and the positioning effect of the suction side cover 36 by caulking is maintained.
[0019]
It is desirable that the thickness t2 of the flange 34 with respect to the main portion thickness t1 of the suction side cover 36 be thin as long as durability can be secured. Further, as the difference between the main part thickness t1 and the flange thickness t2 is larger, the distortion of the suction side cover 36 due to caulking is suppressed, but as the difference is larger, the thickness of the suction side cover 36 is thicker. The axial length of the fuel pump 10 is increased.
[0020]
FIG. 3 is a cross-sectional view showing a process of caulking and joining the suction side cover 36 to the housing 22. The punch 56 is formed with a press surface 58 for pressing the end of the cylindrical housing 22 so as to be in close contact with the flange 34 of the suction side cover 36. The press surface 58 is an annular surface inclined with respect to the central axis of the housing 22. The greater the inclination angle α of the press surface 58 with respect to the central axis of the housing 22, the smaller the stress that distorts the suction side cover 36 convexly toward the impeller side. However, since the housing 22 may be buckled by caulking when the inclination angle α is 45 degrees or more, in this embodiment, the inclination angle α is set to 30 degrees.
[0021]
The press surface 58 may have a conical side surface shape, that is, a shape that appears as a straight line in a cross section including the central axis of the punch 56 (simple taper shape), but the inclination angle with respect to the central axis of the housing 22 increases toward the deeper side. An annular curved surface, that is, a shape (curved taper shape) that appears as a curve in a cross section including the central axis of the punch 56 is desirable. Hereinafter, a punch having a simple tapered press surface is referred to as a flat punch, and a punch having a curved tapered press surface is referred to as a curved punch.
[0022]
FIG. 4 is a graph showing the correlation between the radius of curvature of the press surface 58 (the radius of the arc appearing in the cross section including the center axis of the punch) r1 and the distortion of the flange 34 caused by caulking. This graph shows the result of analyzing the distortion by setting the thickness of the caulking portion of the housing 22 to 0.6 mm. When the curvature radius r2 of the outer peripheral corner of the flange 34 on the side opposite to the pump housing is 1 mm, the distortion of the flange 34 is reduced when the curvature radius r1 of the press surface 58 is 2 mm to 3 mm. When the radius of curvature of the outer peripheral corner r2 on the side opposite to the pump housing of the flange 34 is 2 mm, the distortion of the flange 34 is reduced when the radius of curvature r1 of the press surface 58 is 4 mm to 5 mm. According to this analysis result, when the radius of curvature r1 of the press surface 58 is 1.4 mm to 2.4 mm larger than the sum of the radius of curvature r2 of the flange 34 and the thickness of the housing 22, the distortion of the flange 34 due to caulking is minimized. . In addition, when the radius of curvature r1 of the press surface 58 is 2 to 5 mm, the distortion of the flange 34 due to caulking is always smaller than when the press surface 58 is a simple conical side taper shape.
[0023]
5 and 6 are graphs showing the deformation of the suction side cover 36 by caulking and joining according to the present embodiment. The graph shows the results of analyzing the deformation of the suction side cover 36 under various conditions at two locations, the inner side (point P shown in FIG. 2B) and the outer side (point Q shown in FIG. 2B). Yes. As shown in FIGS. 5 and 6, when the flange 34 is caulked and joined to the housing 22, the suction side cover 36 is fixed to the housing 22 in a state of being distorted in a convex manner on the side opposite to the impeller 37. Further, by using the curved punch, the amount of the suction side cover 36 that is convexly deformed to the anti-impeller side is suppressed as compared with the case where the flat punch is used. The suction side cover 36 and the impeller 37 can be prevented from coming into contact with each other by fixing the suction side cover 36 to the housing 22 in a state of being convexly distorted on the side opposite to the impeller 37.
[0024]
FIG. 7 and FIG. 8 are graphs showing, as a comparative example of the present invention, the strain when the suction side cover 94 without a flange shown in FIG. 10 is caulked and joined to the housing 92. When the suction side cover 94 does not have a flange, the suction side cover 94 is convexly distorted to the impeller side by caulking and fixed to the housing 22 in a state of being convexly distorted to the impeller side, as shown in FIGS. Is done. This result does not matter whether a curved punch is used as shown in FIG. 7 or a flat punch is used as shown in FIG. If the suction side cover 36 is fixed to the housing 22 in a state of being distorted convexly on the impeller side, the suction side cover 36 and the impeller 37 may come into contact with each other.
[0025]
FIG. 9 is a graph showing the thickness t2 of the flange 34 and the distortion of the suction side cover 36 as an analysis value and an average of actual measurement values. The distortion of the suction side cover 36 indicates the value at the point P shown in FIG. Further, the wall thickness t1 of the main part of the suction side cover 36 is always set to 7 mm. As the thickness t2 of the flange 34 is smaller, the stress due to caulking is concentrated on the outer peripheral portion of the suction side cover 36, so that the suction side cover 36 is apt to be distorted convexly toward the anti-impeller side. However, since the fuel pressure inside the housing acts as a force that pushes the flange 34 out of the housing 22, it is possible to ensure sufficient durability by setting the thickness of the flange 34 to be the thickest within a range that does not protrude convexly toward the impeller side. desirable. In the present embodiment, it is most desirable to form a flange 34 having a thickness of 4 mm or more and 5 mm or less, particularly about 4.5 mm, on the suction side cover 36 having a main portion thickness t1 of 7 mm.
[0026]
According to the above-described embodiment, the suction side cover 36 is prevented from being convexly distorted to the impeller side by caulking, so the suction side cover 36 is formed of resin, and the manufacturing cost of the fuel pump 10 can be reduced. Moreover, the fuel pump 10 can be reduced in weight.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a fuel pump according to an embodiment of the present invention.
2A is a plan view showing a suction side cover according to an embodiment of the present invention, FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 2C is a bottom view showing the suction side cover; It is.
FIG. 3 is a cross-sectional view showing a process of caulking and joining a suction side cover according to an embodiment of the present invention to a housing.
FIG. 4 is a graph showing a correlation between a curvature radius r1 of a press surface according to an embodiment of the present invention and a flange distortion caused by caulking.
FIG. 5 is a graph showing deformation of the suction side cover by caulking and joining according to the embodiment of the present invention.
FIG. 6 is a graph showing the distortion of the suction side cover by caulking and joining according to the embodiment of the present invention.
FIG. 7 is a graph showing the distortion of the suction side cover by caulking according to a comparative example of the present invention.
FIG. 8 is a graph showing the distortion of the suction side cover by caulking and joining according to a comparative example of the present invention.
FIG. 9 is a graph showing the thickness t2 of the flange and the strain on the suction side cover according to the embodiment of the present invention as an analysis value and an average of actual measurement values.
FIG. 10 is a cross-sectional view showing a process of caulking and joining a suction side cover according to a comparative example of the present invention to a housing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Fuel pump 12 Fuel discharge port 14 Discharge side cover 22 Housing 32 Boosting flow path 34 Flange 36 Suction side cover 37 Impeller 40 Pump casing 45 Rotating shaft 46 Electric motor 52 Fuel intake port 56 Punch

Claims (5)

A suction side cover having a fuel suction port;
A discharge-side cover having a fuel discharge port;
An electric motor provided between the suction side cover and the discharge side cover;
A pump casing provided between the electric motor and the suction side cover;
A pressure increasing flow path formed between the suction side cover and the pump casing;
An impeller that is housed in the boost channel and rotates together with the rotating shaft of the electric motor;
A fuel pump that includes the suction side cover, the pump casing, and a cylindrical housing that houses the impeller, and supplies fuel in a fuel tank to an internal combustion engine;
The fuel pump according to claim 1, wherein the suction side cover has a flange that is caulked and joined to the housing at an outer peripheral corner portion on the side opposite to the pump casing. The fuel pump according to claim 1, wherein the outer peripheral corner of the flange on the side opposite to the pump casing is rounded. The fuel pump according to claim 2, wherein a radius of curvature of an outer peripheral corner portion of the flange on the side opposite to the pump casing is 2 mm or more. 4. The fuel pump according to claim 2, wherein the flange and the housing are caulked and joined using a curved surface of a punch whose inclination angle with respect to a central axis of the housing increases toward a deeper side. The thickness of the said flange is 4 mm or more and 5 mm or less, The fuel pump as described in any one of Claims 1-4 characterized by the above-mentioned.

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